FPC: acid base made easy Flashcards
You look at a patient’s pH and they have a low pH with low bicarb. What is this?
Metabolic acidosis
You look at a patient’s pH and they have a low pH with high pCO2. What is this?
Respiratory acidosis
You look at a patient’s pH and they have a high pH with high bicarb. What is this?
Metabolic alkalosis
You look at a patient’s pH and they have high pH with low pCO2. What is this?
Respiratory alkalosis
What is normal pH?
7.35-7.45
A pH less than ___ is incompatible with life.
6.8
A pH greater than ___ is incompatible with life.
8.0
What acid does aerobic metabolism produce?
Carbonic acid
What acid does anaerobic metabolism produce?
Lactic, phosphoric, sulfuric acids
What is a buffer pair?
Combination of acid and base that prevents pH changes. This is a strong base and weak acid.
How can we use pCO2 to find carbonic acid?
pCO2 x 0.03
What is the Henderson-Hasselbach equation?
What is a simple formula for pH?
(HCO3-)/pCO2
How can we measure acid-base from arterial blood?
pH, pCO2, calculated bicarb
How can we measure acid-base from venous blood?
Bicarb, Na+, K+, Cl-
How do the lungs contribute to acid-base balance?
Removes acid via exhalation of carbonic acid as H2O and CO2.
How do the kidneys contribute to acid-base balance?
Removes acid via excreting acid phosphate and ammonium ion and reabsorption of Na+ and bicarb in exchange for a proton.
In what case do we see Kussmaul breathing? Why?
In metabolic acidosis; there is decreased bicarb that causes decreased pH. We can compensate via these rapid deep breaths that blow off CO2 to prevent pH from dropping too much.
How do we measure unmeasured anions?
Anion gap
What can give you metabolic acidosis with normal anion gap?
Diarrhea, renal tubular acidosis, hyperalimentation, early renal failure.
What are some acid loss causes of metabolic alkalosis?
Vomiting and gastric drainage.
What are some alkali gain causes of metabolic alkalosis?
Cl or K depletion via diuretics, mineralocorticoid excess, bicarb gain, and organic anions via blood transfusion.
Describe the relationship between K+ and H+ in cells.
They oppose each other in a way; hypokalemia may draw more H+ into the cell, and high proton content leads to proton entering the cell, which may drive K+ out of the cell.
What are acute causes of respiratory acidosis?
Sudden airway obstruction, chest trauma, acute paralysis, depression of CNS respiratory centers.
What are chronic causes of respiratory acidosis?
COPD, pulmonary fibrosis.
Describe pH, HCO3, and pCO2 in respiratory acidosis.
High bicarb, low pH, high pCO2.
Describe pH, HCO3, and pCO2 in respiratory alkalosis.
High pH, low pCO2, low bicarb.
Which acid-base disorder can we cause acutely by ourselves?
Respiratory alkalosis via hyperventilation.
A patient has cerebral edema. Which breathing mechanism would you want to induce?
Respiratory alkalosis; this decreases flow to relieve intracranial pressure.
Describe aspirin overdose.
A mixed disorder beginning with respiratory alkalosis followed by metabolic acidosis.
